Refactor timestamp handling in FileTranscriptStore and update related tests for consistency (#166)

Author: cleemullins

libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/storage/transcript_file_store.py

@@ -71,7 +71,7 @@ async def log_activity(self, activity: Activity) -> None:
         def _write() -> None:
             # Normalize to a dict to ensure json serializable content.
             if not activity.timestamp:
-                activity.timestamp = _utc_iso_now()
+                activity.timestamp = datetime.now(timezone.utc)
 
             with open(file_path, "a", encoding="utf-8", newline="\n") as f:
                 f.write(activity.model_dump_json(exclude_none=True, exclude_unset=True))
@@ -261,7 +261,3 @@ def _to_plain_dict(activity: Activity) -> Dict[str, Any]:
             "conversation": {"id": conversation_id},
             "text": getattr(activity, "text", None),
         }
-
-
-def _utc_iso_now() -> str:
-    return datetime.now(timezone.utc).isoformat()

tests/hosting_core/storage/test_file_transcript_storage.py

@@ -134,8 +134,8 @@ async def test_get_transcript_activities_with_paging(temp_logger: FileTranscript
 async def test_get_transcript_activities_with_start_date_filter(
     temp_logger: FileTranscriptStore,
 ):
-    old_ts = (datetime.now(timezone.utc) - timedelta(days=2)).isoformat()
-    new_ts = datetime.now(timezone.utc).isoformat()
+    old_ts = datetime.now(timezone.utc) - timedelta(days=2)
+    new_ts = datetime.now(timezone.utc)
 
     activity1 = make_activity(conv="filtered", text="old")
     activity2 = make_activity(conv="filtered", text="new")